Because right now, had the thieves been caught AND prosecuted, they would have to be put in jail, which is Known in the State of California to be Undesirable (/s, but not /s). This, plus the legislation that any theft < $950 is a misdemanor, means that the police never bother going after them.

OTOH, if the alternative is instant corporal punishment (without clogging up the lines at the jail), then perhaps the laws can actually be enforced?